If you’re a developer, the next step is to write your own CorDapp. CorDapps are applications that are installed on one or
more Corda nodes, and that allow the node’s operator to instruct their node to perform some new process - anything from
issuing a debt instrument to making a restaurant booking.

We will write a CorDapp to model IOUs on the blockchain. Each IOU – short for “I O(we) (yo)U” – will record the fact that one node owes
another node a certain amount. This simple CorDapp will showcase several key benefits of Corda as a blockchain platform:

Privacy - Since IOUs represent sensitive information, we will be taking advantage of Corda’s ability to only share
ledger updates with other nodes on a need-to-know basis, instead of using a gossip protocol to share this information with every node on
the network as you would with a traditional blockchain platform

Well-known identities - Each Corda node has a well-known identity on the network. This allows us to write code in terms of real
identities, rather than anonymous public keys

Re-use of existing, proven technologies - We will be writing our CorDapp using standard Java. It will run on a Corda node, which is
simply a Java process and runs on a regular Java machine (e.g. on your local machine or in the cloud). The nodes will store their data in
a standard SQL database

CorDapps usually define at least three things:

States - the (possibly shared) facts that are written to the ledger

Flows - the procedures for carrying out specific ledger updates

Contracts - the constraints governing how states of a given type can evolve over time

Our IOU CorDapp is no exception. It will define the following components: